In the rubber industry, textile fabrics are used as reinforcement layers in the manufacture of products subjected to dynamic loads such as tires, conveyor belts and air springs. The durability of these products is dependent upon the adherence between the reinforcement layer and the elastomeric matrix.
Fabrics made of synthetic fibers such as nylon fibers are mostly used as reinforcement layers. Compared to natural fibers, these synthetic fibers have outstanding characteristics such as excellent performance with respect to alternating flexural stresses, high tear resistance and a uniform expansion capability. A disadvantage is seen in that the surface of the synthetic cords is smooth and not very compatible with rubber.
It is known to treat the fabric in advance of the application of rubber to obtain good adherence. For this purpose, the fabric is guided through a dip containing an aqueous two-component solution of synthetic resin and latex. Resorcinol formaldehyde is used in most cases as the synthetic resin solution while the latex is usually a vinyl-pyridine latex. The fabric prepared in this manner is then dried. A fabric treated in accordance with the above two operations will hereinafter be referred to as a "latexed fabric".
The latexed fabric is rubberized with a polar rubber stock such as polychloroprene rubber (CR) so that the fabric can be bonded well to the elastomeric matrix by vulcanization to form a whole.
U.S. Pat. No. 4,210,475 is incorporated herein by reference and discloses a method for treating tire cords to obtain a good rubber-to-cord adherence. Here too, an aqueous adhesive interface solution (dip) is utilized. In this method, the conventional resorcinol-formaldehyde resin is replaced with lignin sulfonate.
Although the methods described above and the interface adhesive systems have been proven, the increasing production requirements do not always permit a satisfactory service life to be obtained with products which are very highly stressed dynamically such as air springs in the area of motor vehicles. The high alternating flexural stress is the cause for a possible destruction of the particular rubber product with respect to the bond of the cord fabric and rubber.